GnRH antagonist Pregnancy: US label CONTRAINDICATIONS: contraindicated in known or suspected pregnancy and in lactation. No section 4.6 equivalent was available in this bundle - verify against the UK SPC.

Cetrorelix

Brand names: Cetrotide

Cetrorelix is a gonadotrophin-releasing hormone (GnRH) antagonist used during controlled ovarian stimulation in assisted reproduction to prevent premature ovulation.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 0.25 mg

Route: Subcutaneous injection into the lower abdominal area, preferably around but at least one inch away from the navel; a different injection site should be chosen each day to minimise local irritation

Frequency: Once daily

openFDA / DailyMed US prescribing information (cetrorelix acetate for injection 0.25 mg, Gland Pharma) - no UK SPC was available in this bundle, so the regimen must be checked against the UK SPC (Cetrotide) before publication. Ovarian stimulation therapy with gonadotropins (FSH, hMG) is started on cycle day 2 or 3, with the gonadotropin dose adjusted according to individual response. Cetrorelix 0.25 mg may be administered subcutaneously once daily during the early- to mid-follicular phase; it is administered on either stimulation day 5 (morning or evening) or day 6 (morning) and continued daily until the day of hCG administration. When assessment by ultrasound shows a sufficient number of follicles of adequate size, hCG is administered to induce ovulation and final maturation of the oocytes. No hCG should be administered if the ovaries show an excessive response to gonadotropin treatment, to reduce the chance of developing ovarian hyperstimulation syndrome (OHSS). May be self-administered by the patient after appropriate instruction by her doctor. REGIMEN GAP: the 3 mg single-dose regimen shown on this page is NOT described in the fetched US label, which covers only the 0.25 mg daily presentation - source the 3 mg SPC separately before publishing that regimen.

Dose auto-extracted from US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to cetrorelix acetate, extrinsic peptide hormones or mannitol (US label)
Known hypersensitivity to GnRH or any other GnRH analogues (US label)
Known or suspected pregnancy, and lactation (US label)
Severe renal impairment (US label)

Side effects

Ovarian hyperstimulation syndrome, moderate or severe (3.5% in clinical studies); mild to moderate OHSS also reported post-marketing
Nausea (1.3%)
Headache (1.1%)
Local injection site reactions - redness, erythema, bruising, itching, swelling and pruritus; usually transient, mild and of short duration
Hypersensitivity reactions including anaphylactoid reactions (post-marketing surveillance)

Clinical monograph

How it works

It competitively blocks pituitary GnRH receptors, producing an immediate, dose-dependent suppression of luteinising hormone and thereby preventing a premature LH surge.

Prescribing in practice

It must be used as part of a specialist-supervised assisted conception protocol to prevent premature ovulation, with timing relative to gonadotrophin stimulation defined by the protocol.
Unlike GnRH agonists it produces immediate suppression without an initial flare, so it is started during ongoing follicular stimulation.
Local injection-site reactions are common and ovarian hyperstimulation syndrome remains a risk of the overall stimulation cycle.

Monitoring

Ovarian response is monitored by ultrasound follicle tracking and hormone levels as part of the stimulation cycle.

Counselling the patient

This injection prevents your eggs being released too early during fertility treatment.
Injection-site redness or itching is common and usually mild.
Report severe abdominal pain, bloating, or breathlessness, which may indicate ovarian hyperstimulation.

Evidence & guidelines

GnRH antagonist protocols are an established approach in assisted reproduction and are associated with a lower risk of ovarian hyperstimulation syndrome than long agonist protocols.

Reference: Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

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